I have only used the AA and they have been pretty good. Even when stuck down a country lane, they arrived within half an hour Over the last 20 years or so, I have broken down about 4 times. 3 fixed by the roadside as not major faults and 1 towed to garage.
I did have the RAC cover for a period and did not use them. I suppose it depends on the faults and where the car is situated when broken down. All roadside assistance companies will only spend a restricted amount of time at the roadside and the car has to be situated in a safe place for them to do the work.